Electrolytic capacitor and its manufacturing method

ABSTRACT

An electrolytic capacitor includes a capacitor element having a positive electrode, a negative electrode, and a solid organic conductive material disposed between the positive and the negative electrode, an electrolyte, a case for accommodating the capacitor element and the electrolyte, and a sealing member disposed to cover the opening of the case. The solid organic conductive material has at least one material selected from organic semiconductor and conductive polymer. The electrolytic capacitor having excellent impedance characteristic, small current leak, excellent reliability, and high dielectric strength.

FIELD OF THE INVENTION

The present invention relates to an electrolytic capacitor as anelectronic component, and its manufacturing method.

BACKGROUND OF THE INVENTION

In the recent trend of electronic appliances becoming digital and higherin frequency, the electrolytic capacitor, one of the electroniccomponents, is required to be larger in capacity than in theconventional part and is superior in impedance characteristic in highfrequency region. To meet such demand, it has been attempted to enhancethe conductivity of the driving electrolyte (hereinafter calledelectrolyte), decrease the resistance of separator, or use a conductivecompound obtained by making conductive a sheet insulator such as paper,cloth, nonwoven cloth or high polymer film, as a separator.

Also as an attempt to make the separator conductive, various methodshave been proposed, such as kneading or mixing of carbon fibers orparticles, and compounding with graphite powder. Moreover, by usingmonomer such as pyrrole, thiophen or aniline, a method of forming aconductive high polymer on the surface by chemical oxidation andpolymerization is disclosed (see Japanese Laid-open Patent No.64-90517).

In the conventional constitution, however, there was a limit inenhancement of conductivity of electrolyte, and its conductivity is atmost about ten to scores of mS/cm at the present, and electrolyte havinga sufficient conductivity is not developed yet, and an electrolyticcapacitor of an electrolyte having a sufficient impedance characteristicis not obtained so far.

On the other hand, for decrease of resistance of separator, it has beenattempted to decrease the separator thickness, lower the density, makeuniform the pore size, or change from paper to high polymer nonwovenfabric, but due to lack of strength by lowering of density and otherproblems, a sufficient effect of lowering the resistance is not obtainedyet.

Further, the separator made conductive by kneading or mixing carbonfibers or particles is not sufficient in the electric conductivity, andit was hard to obtain a separator of low density. When using a separatorby compounding graphite powder, there was a problem of increase ofshorting due to drop of graphite powder and dispersion into electrolyte.

On the other hand, in the method of forming a conductive high polymer onthe surface by chemical oxidation and polymerization from monomer ofpyrrole, thiophen or aniline, it is difficult to compose an electrolyticcapacitor of which rated voltage exceeds 35 V because there is almost noeffect of deterioration of dielectric oxide film by oxidizing agent orchemical formation of conductive high polymer (defect repairingcapability of dielectric oxide film). If composed, however, increase ofleak current or shorting between anode and cathode may occur duringagent process or high temperature test.

It is hence an object of the invention to present an electrolyticcapacitor of high dielectric strength excellent in impedancecharacteristic, leak current property and reliability.

SUMMARY OF THE INVENTION

An electrolytic capacitor of the invention comprises:

(a) a capacitor element having an anode, a cathode, and a solid organicconductive material disposed between the anode and the cathode,

(b) an electrolyte,

(c) a case for accommodating the capacitor element and the electrolyte,and

(d) a sealing member disposed to cover the opening of the case.

A manufacturing method of electrolytic capacitor of the inventioncomprises:

(a) a step of fabricating an anode,

(b) a step of fabricating a cathode,

(c) a step of forming a solid organic conductive material on the surfaceof the anode, and

(d) a step of disposing an electrode between the anode having the solidorganic conductive material and the cathode.

In this constitution, an electrolytic capacitor having an excellentimpedance characteristic, an excellent leak current characteristic, anexcellent reliability, and a high dielectric strength is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a partial sectional perspective view showing a constitutionof an electrolytic capacitor according to a first embodiment of theinvention.

FIG. 1(b) is a schematic diagram magnifying the essential parts of theelectrolytic capacitor element shown in FIG. 1(a).

FIG. 2 is a manufacturing process diagram for manufacturing the anodefoil of an electrolytic capacitor of the invention.

DETAILED DESCRIPTION OF THE INVENTION

An electrolytic capacitor of the invention comprises a case having anopening, an electrolyte contained in the case, a capacitor elementplaced in the electrolyte, and a sealing member disposed to cover theopening. The capacitor element has an anode, a cathode, and a solidorganic conductive material installed between the anode and cathode.

In this constitution, by making use of the high electric conductivity ofthe solid organic conductive material, the interpolar resistance in theconductive portion can be extremely decreased, and hence the impedancecharacteristic is enhanced. Further, by using together with theelectrolyte having the repair capability of dielectric oxide film ofvalve action metal, an electrolytic capacitor of low leak current havinga high dielectric strength is obtained.

In the invention, as the solid organic conductive material, an organicsemiconductor is preferred, and preferred examples of organicsemiconductor include 7,7,8,8-tetra-cyanoquinodimethane complex and itsderivatives (hereinafter called TCNQ complexes). In this constitution,by dissolving and impregnating TCNQ complexes, a layer of solid organicconductive material having a high conductivity may be filledsufficiently to the inside of the pit of the anode processed by etching.As a result, an electrolytic capacitor excellent in impedancecharacteristic particularly in a high frequency region over 100 kHz canbe obtained. Still more, TCNQ complexes can be directly applied on aseparator base material. Moreover, a capacitor element winding an anodefoil and a cathode foil through a separator base material can bemanufactured. Alternatively, a capacitor element laminating one set ortwo sets or more of anode and cathode through separator base materialmay be impregnated in a heated and dissolved TCNQ complex solution, andby cooling and solidifying, the conductivity may be easily expressed. Asa result, an electrolytic capacitor having an excellent impedancecharacteristic may be easily obtained.

In the invention, the word of “anode” means “positive electrode”, andthe word of “cathode” means “negative electrode”. The word of“conductive high polymer” means “conductive polymer”.

In the invention, the conductive high polymer includes pyrrole, aniline,thiophen, ethylene dioxythiophen, sulfonated aniline, sulfonatedpyrrole, sulfonated thiophen, sulfonated ethylene dioxythiophen, theirderivatives, and polymers of various polymerizable monomers.

Methods of forming such polymers include a method by liquid-phasechemical polymerization, a method by vapor-phase chemicalpolymerization, a method by liquid-phase electrolytic polymerization,and a method by drying soluble high polymer solution and utilizingresidual high polymer.

Usable examples of conductive high polymer include polypyrrole,polyethylene dioxythiophen, or polyaniline formed by chemicalpolymerization or electrolytic polymerization, and dry residualsulfonated polyaniline obtained by drying solutions of solublepolyanilines.

In liquid-phase polymerization, in a solution containing at least thepolymerizable monomer and a proper oxidizing agent, a capacitor elementis immersed, and polymerized. In the case of an electrolyticpolymerization, in a solution containing at least the polymerizablemonomer and a proper oxidizing agent, a capacitor element is immersed,and power is supplied to polymerize it. In the case of vapor-phasepolymerization, in a solution containing at least a proper oxidizingagent, a capacitor element is immersed (or immersed, lifted and dried),and then in the vapor phase containing at least the polymerizablemonomer, the capacitor element is placed. By these methods, a layer ofsolid organic conductive material having a high conductivity can besufficiently applied into the inside of pits of the anode processed byetching. As a result, an electrolytic capacitor having an excellentimpedance characteristic also in a high frequency region of over 100 kHzin particular is obtained. Moreover, by polymerizing the conductive highpolymer directly in the separator base material, anode or cathode invapor phase, the conductivity can be easily expressed. As a result, anelectrolytic capacitor having an excellent impedance characteristic maybe easily obtained.

Further, since these conductive high polymers have a high compatibilityin an electrolyte composed of an organic matter, when impregnated withthe electrolyte, it is quickly swollen and diffused into the inner partsof the conductive high polymer. Accordingly, when composing a capacitorelement having the dielectric oxide film coated with conductive highpolymer, the capacity for restoring the dielectric oxide film can bemaintained at high level.

The electrolyte comprises an electrolytic substance such as salt oforganic acid or salt of inorganic acid, and a solvent for dissolvingsuch electrolytic substances. As such organic solvent, an organicsolvent capable of swelling an organic conductive material by immersingit is preferred. In this constitution, as mentioned above, theelectrolyte quickly swells and diffuses into the inner part of theconductive high polymer. Therefore, when composing a capacitor elementhaving the dielectric oxide film coated with conductive high polymer,the capacity for restoring the dielectric oxide film can be maintainedat high level.

As the electrolytic substance to be dissolved in the electrolyte, in abase for composing the electrolyte, when the concentration of the baseor hydroxide of base is 1 wt. % and the measuring temperature is 30° C.,the hydrogen ion concentration in aqueous solution of base or hydroxideof base is usable at 1.0×10⁻¹³ mol/dm³ or more. As its specific example,as the base for composing the electrolytic substance, at least one isused as being selected from the group consisting of compound havingalkyl substituent amidine group, quaternary salt of compound havingalkyl substituent amidine group, tertiary amine and ammonium. In thisconstitution, leak of electrolyte is prevented, and a capacitor ofenhanced reliability is obtained.

When composing a capacitor by using an electrolyte composed of anelectrolytic substance of a base of a strong basicity of which hydrogenion concentration is less than 1.0×10⁻¹³ mol/dm³ (for example,tetra-alkyl ammonium or tetra-alkyl phosphonium), in long-termenvironmental test in the compound environments of high temperature andhigh humidity (for example, 60° C. and 95% RH), the sealing member islikely to be damaged by the effects of the base of strong basicity, andleak is likely to occur, and the reliability is slightly inferior.

As the base for composing the electrolytic substance, at least one ispreferred to be used as being selected from the group consisting ofcompound having alkyl substituent amidine group, quaternary salt ofcompound having alkyl substituent amidine group, tertiary amine andammonium. In these electrolytic substances, when the concentration ofthe base or hydroxide of base is 1 wt. % and the measuring temperatureis 30° C., the hydrogen ion concentration in aqueous solution of base orhydroxide of base is 1.0×10⁻¹³ mol/dm³ or more. Accordingly, the leakdue to such strong acidity as mentioned above is less likely to occur.

As the quaternary salt of compound having alkyl substituent amidinegroup, a quaternary compound formed by alkyl group or aryl alkyl groupwith 1 to 11 carbon atoms is preferred, and such compound is oneselected from the group consisting of imidazole compound, benzoimidazolecompound, and alicyclic amidine compound. In this constitution, whenhydroxide ions are formed by electrolytic reaction in the electrolyte,since the reaction between hydroxide ion and amidine group of N-C-N orreaction of decomposition and ring opening is fast, the electrolyticproducts disappear quickly. As a result, even in the condition of hightemperature and high humidity, leak of electrolyte to outside can beprevented.

The quaternary salt of compound having alkyl substituent amidine groupis at least one selected from the group consisting of1-methyl-1,8-diazabicyclo [5,4,0] undecene-7, 1-methyl-1,5-diazabicyclo[4;3,0] nonene-5, 1,2,3-trimethyl imidazolinium, 1,2,3,4-tetramethylimidazolinium, 1,2-dimethyl-3-ethyl-imidazolinium,1,3,4-trimethyl-2-ethyl imidazolinium, 1,3-dimethyl-2-heptylimidazolinium, 1,3-dimethyl-2-(-3′ heptyl) imidazolinium,1,3-dimethyl-2-dodecyl imidazolinium,1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidium, 1,3-dimethyl imidazolium,1-methyl-3-ethyl-imidazolium, and 1,3-dimethyl benzoimidazolium.According to this constitution, the conductivity of the electrolyte canbe heightened and an excellent heat resistance is realized. Therefore,external leak of electrolyte at high temperature and high humidity isprevented, and an electrolytic capacitor having an excellent hightemperature stability and low impedance is obtained.

The boiling point of the solvent of the electrolyte is 200° C. or more,the conductivity at measuring temperature of 30° C. of the electrolyteis 1.0 mS/cm or more, and the spark ignition voltage is 80 V or more. Inthis constitution, it is effective to prevent the problem ofelectrolytic capacitor for surface mounting, that is, deformation ofappearance due to elevation of capacitor internal pressure caused byheat treatment during surface mounting (both capacitor and substrateexposed to high temperature of soldering). Moreover, since the boilingpoint of the solvent of the electrolyte is high (vapor pressure is low),defective soldering when mounting is less likely to occur, and furthersince the conductivity is high, the impedance performance is maintained.Still more, since the spark ignition voltage is sufficiently high, anelectrolytic capacitor having a high dielectric strength is obtained.

The sealing member is composed by using an elastic rubber. In the solidelectrolytic capacitor for surface mounting using this elastic rubber,the adsorbed moisture contained in the electrode foil of capacitorelement, separator, solid electrolytic substance and rubber sealingmember, or the adsorbed moisture bonded to the inside of the case isevaporated at once at high temperature at the time of surface mounting.As a result, the pressure elevation inside the capacitor is extreme,which may lead to defective air tightness of the capacitor or scatteringof sealing member. However, by containing the electrolyte using asolvent of high boiling point (low vapor pressure), the total pressureinside the capacitor can be lowered at the time of mounting. Therefore,by containing the liquid component (herein an electrolytic solution) inaddition to the electrolytic substance of solid electrolytic substancetype, pressure elevation inside the capacitor can be suppressed, anddefective soldering and others can be improved.

Examples of solvent of electrolyte having a boiling point of 200° C. ormore include 3-alkyl-1,3-oxazolidine-2-one (more specifically,3-methyl-1,3-oxazolidine-2-one: boiling point 260° C.),1,3-dialkyl-2-imidazolidinone other than 1,3-dimethyl-2-imidazolidinone(more specifically, 1,3-dimethyl-2-imidazolidinone: boiling point 236°C., 1,3-dipropyl-2-imidazolidinone: boiling point 255° C.,1-methyl-3-ethyl-2-imidazolidinone: boiling point 230° C.),1,3,4-trialkyl-2-imidazol:idinone (more specifically,1,3,4-trimethyl-2-imidazolidinone: boiling point 241° C.),1,3,4,5-tetra-alkyl-2-imidazolidinone (more specifically,1,3,4,5-tetramethyl-2-imidazolidinone: boiling point 249° C.), cycliclactone (more specifically, γ-butyrolactone: boiling point 204° C.),polyhydric alcohol (more specifically, ethylene glycol: boiling point201° C., glycerin: boiling point 290° C.), carbonate (more specifically,ethylene carbonate: boiling point 238° C., propylene carbonate: 242°C.), and others.

Hereinafter, preferred embodiments of the invention and prior arts ascomparative examples are described below while referring to the attacheddrawings.

FIG. 1(a) and FIG. 1(b) are a partial sectional perspective view showinga constitution of an electrolytic capacitor of the invention, and aconceptual view magnifying essential parts of its element. In FIG. 1(b),the surface is roughened by etching process, and then a dielectric oxidefilm 11 is formed by oxidation treatment. An anode foil 1 composed of analuminum foil forming a solid organic conductive material 2 on itssurface, and a cathode foil 3 formed by etching an aluminum foil arewound around a separator 4. Or, after roughening the surface by etchingprocess, an anode foil 1 composed of an aluminum foil forming adielectric oxide film 11 by oxidation treatment and a cathode foil 3formed by etching process of aluminum foil are wound through anelectrolytic paper 4A. Then by high temperature treatment thereof, theelectrolytic paper 4A is treated by any method of carbonizationtreatment, and a capacitor element 12 or 12A is formed. Between thedielectric oxide film 11 and cathode foil 3, a solid organic conductivematerial 2 is formed. It is impregnated with an electrolyte 10, andswollen and infiltrated into the solid organic conductive material 2.Thus, the capacitor element 12 or 12A is composed. The capacitor element12 or 12A is put in a cylindrical aluminum metallic case 8 with a bottomas shown in FIG. 1(a). Further, the releasing end of the aluminummetallic case 8 is sealed so that a sealing member 7 made of rubber maypenetrate through an anode lead 5 and a cathode lead 6 for externallead-out being led out from the anode foil 1 and cathode foil 3 from thesealing member 7. Thus, the side surface of the metallic case 8 iscovered with an external tube 9.

FIG. 2(a) to FIG. 2(g) show the manufacturing process for manufacturingthe anode foil 1 for electrolytic capacitor of the invention in batch.As shown in FIG. 2 (a), an etching foil 22 (FIG. 2(b)) obtained byetching an aluminum foil 21 is oxidized. In this way, an anode foil 1forming a dielectric oxide film 11 is formed (FIG. 2(c)). Successively,this anode foil 1 is impregnated in a solution 23 containing apolymerizable monomer capable of forming a conductive high polymer layeras shown in FIG. 2 (d), and lifted, then heated (also dried) by aheating oven 24 as shown in FIG. 2(e). Thus, as shown in FIG. 2(f), ananode foil 1 forming a solid organic conductive material 2 on thesurface is composed. Next, as shown in FIG. 2(g), thus constituted anodefoil 1 and the cathode foil 3 formed by etching the aluminum foil 21 arewound through a separator 4. In this way, a capacitor element 12 iscomposed. The subsequent process is same as in the above manufacturingmethod. The capacitor element 12 is put into a cylindrical metallic case8 with a bottom together with electrolyte 10. The releasing end of themetallic case 8 is sealed, by using a sealing member 7, so that an anodelead 5 and a cathode lead 6 for external lead-out being led out from theanode foil 1 and cathode foil 3 respectively may penetrate through thesealing member 7. Thus, the side of the metallic case 8 is covered withan external tube 9.

The electrolyte used in the electrolytic capacitor of the invention isspecifically described below.

As the solvent for the electrolyte of the electrolytic capacitor of theinvention, an organic solvent stable electrically and chemically andcapable of swelling in the organic conductive material is used. Suchorganic solvent is desired to have a boiling point of 200° C. or more.The solvent is preferred to be mainly composed of γ-butyrolactone and/orethylene glycol. In addition, for the purpose of improving the lowtemperature characteristic and enhancing the dielectric strength, otherorganic solvent compatible with γ-butyrolactone and/or ethylene glycolmay be mixed as a subsidiary solvent. Nevertheless, the subsidiarysolvent is not required to be an organic solvent capable of swelling inan organic conductive material.

As the subsidiary solvent, in addition to the organic solvent withboiling point of 200° C. or more mentioned above, the following organicsolvents may be used either alone or as a mixed solvent of two or morekinds, that is, polyhydric alcohol system solvents (propylene glycol,diethylene glycol, 1,4-butane diol, polyoxy alkylene polyol), lactonesystem solvents (γ-valerolactone, δ-valerolactone,3-ethyl-1,3-oxyzolidine-2-one), water, amide system solvents (N-methylformamide, N,N-dimethyl formamide, N-methyl acetamide), ether systemsolvents (methylal, 1,2-dimethoxy ethane, 1-ethoxy-2-methoxy ethane,1,2-diethoxy ethane), nitrile system solvents (acetonitrile, 3-methoxypropionitrile), furane system solvents (2,5-dimethoxy tetrahydrofurane),2-imidazolidinone system solvents (1,3-dimethyl-2-imidazolidinone), andothers.

In the case of mixed solvent, the mixing ratio of the solvent ispreferred to be 40 parts by weight of a solvent of which boiling pointis less than 200° C. in 100 parts by weight of solvent of which boilingpoint is 200° C. or more. If the content of the solvent of which boilingpoint is less than 200° C. is more than 40 parts, the heat resistance islowered when an electrolytic capacitor is formed for surface mounting,and the defective rate of soldering becomes higher.

Examples of tertiary amine used in the electrolyte of the inventioninclude trialkylamines (trimethylamine, dimethylethylamine,methyldiethylamine, triethylamine, dimethyl n-propylamine, dimethylisopropylamine, methyl ethyl n-propylamine, methylethyl isopropylamine,diethyl n-propylamine, diethyl isopropylamine, tri-n-propylamine,tri-isopropylamine, tri-n-butylamine, tri-tert-butylamine, etc.), andphenyl group containing amines (dimethyl phenylamine, methylethylphenylamine, diethyl phenylamine, etc.).

Among them, trialkylamine having a high conductivity is preferred. Morepreferably, it is preferred to use at least one selected from the groupconsisting of trimethylamine, dimethylethylamine, methyl diethylamine,and triethylamine, and by the use thereof, a capacitor high inconductivity and having an excellent impedance performance is obtained.

Examples of compound having alkyl substituent amidine group used in theelectrolyte of the invention include imidazole compound, benzoimidazolecompound, and alicyclic amidine compound (pyrimidine compound,imidazoline compound). More specifically, it is preferred to use1,8-diazabicyclo [5,4,0] undecene-7, 1,5-diazabicyclo [4,3,0] nonene-5,1,2-dimethyl imidazolinium, 1,2,4-trimethyl imidazoline,1-methyl-2-ethyl-imidazoline, 1,4-dimethyl-2-ethyl imidazoline,1-methyl-2-heptyl imidazoline, 1-methyl-2-(3′ heptyl) imidazoline,1-methyl-2-dodecyl imidazoline,1,2-dimethyl-1,4,5,6-tetrahydropyrimidine, 1-methyl imidazole, and1-methyl benzoimidazole, and when these compounds are used, a capacitorhaving a high conductivity and excellent impedance performance isobtained.

In the examples of quaternary salt of compound having alkyl substituentamidine group used as the electrolyte is preferred to be a quaternarycompound formed by alkyl group or aryl alkyl group with 1 to 11 carbonatoms is preferred, and preferred examples of amidine group areimidazole compound, benzoimidazole compound, and alicyclic amidinecompounds (pyrimidine compound, imidazoline compound). Specificpreferred examples include 1-methyl-1,8-diazabicyclo [5,4,0] undecene-7,1-methyl-1,5-diazabicyclo [4,3,0] nonene-5, 1,2,3-trimethylimidazolinium, 1,2,3,4-tetramethyl imidazolinium,1,2-dimethyl-3-ethyl-imidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2-heptyl imidazolinium, 1,3-dimethyl-2-(-3′heptyl) imidazolinium, 1,3-dimethyl-2-dodecyl imidazolinium,1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidium, 1,3-dimethyl imidazolium,1-methyl-3-ethyl-imidazolium, and 1,3-dimethyl benzoimidazolium. Byusing these compounds, it is possible to obtain an electrolyticcapacitor with an excellent long-term stability having a high heatresistance, high conductivity, and excellent impedance performance.

Examples of organic acid used in the electrolyte of the inventioninclude the following compounds: polycarboxylic acid (valence of 2 to4), aliphatic polycarboxylic acid (saturated polycarboxylic acid, forexample, oxalic acid, malonic acid, succinic acid, glutaric acid, adipicacid, pimelic acid, suberic acid, azelaic acid, sebatic acid,1,6-decanoic dicarboxylic acid, 5,6-decanoic dicarboxylic acid,1,7-octanoic dicarboxylic acid, and unsaturated polycarboxylic acid, forexample, maleic acid, fumaric acid, itaconic acid, aromaticpolycarboxylic acid (for example, phthalic acid, isophthalic acid,terephthalic acid, trimellitic acid, pyromellitic acid), alicyclicpolycarboxylic acid (for example, cyclohexane-1,2-dicarboxylic acid,cyclohexene-1,2-dicarboxylic acid, etc.), hexahydrophthalic acid, alkylsubstituents with 1 to 3 carbon atoms of their polycarboxylic acids (forexample, citraconic acid, dimethyl maleic acid), or nitro substitutes(nitrophthalic acid, 3-nitrophthalic acid, 4-nitrophthalic acid), andpolycarboxylic acid containing sulfur (for example, thiopropionic acid),monocarboxylic acid, aliphatic monocarboxylic acid with 1 to 30 carbonatoms (for example, formic acid, acetic acid, propionic acid, butyricacid, isobutyric acid, valeric acid, caproic acid, enanthic acid,caprylic acid, perargonic acid, lauric acid, mystyric acid, stearicacid, behenic acid, other saturated carboxylic acid, and acrylic acid,methacrylic acid, oleic acid, and other unsaturated carboxylic acid),aromatic monocarboxylic acid (for example, benzoic acid, o-nitrobenzoicacid, p-nitrobenzoic acid, cinnamic acid, naphthoic acid), andoxycarboxylic acid (for example, salicylic acid, mandelic acid,resorcylic acid). Among these compounds, particularly preferredcompounds are those having high conductivity and excellent thermalconductivity such as maleic acid, phthalic acid, cyclohexane carboxylicacid, cyclohexene-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylicacid, adipic acid, and benzoic acid.

The ratio of organic acid and base for composing the electrolyte isusually 4 to 11 at the pH of the electrolyte, and preferably 6 to 9. Outof this range, the spark voltage of the electrolyte (dielectricstrength) is lowered.

As the electrolytic salt, organic carboxylic acids stable electricallyand chemically are desired. Preferred examples of such organiccarboxylic acid include maleic acid, phthalic acid, cyclohexanecarboxylic acid, cyclohexene-1,2-dicarboxylic acid,cyclohexene-1,2-dicarboxylic acid, adipic acid, and quaternary salt ofcompound having alkyl substituent amidine group of benzoic acid.

The electrolyte of the electrolytic capacitor of the invention may mixand contain various additives as required. Usable additives includephosphor compounds (phosphoric acid, ester phosphate, etc.), boric acidcompounds (boric acid, complex of boric acid and polysaccharides(mannite, sorbit, etc.)), nitro compounds (o-nitrobenzoic acid,n-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol,p-nitrophenol, p-nitroacetophenone, etc.), and others. In the aluminumelectrolytic capacitor, mixing of these additives will improve therestoration of aluminum oxide film. As a result, it is preferred becausean electrolytic capacitor of high dielectric strength can be formedeasily.

As the bar element for the terminal of the electrolytic capacitor of theinvention, a material undergoing corrosion preventive treatment may beused. By corrosion preventive treatment of the bar element, electrolyticcurrent can be suppressed, and the sealing performance may be enhanced.Corrosion preventive treatment of the bar element is preferred to bedone on both terminals of anode and cathode, but only either one may betreated. As means of corrosion preventive treatment, anode oxidationtreatment in aqueous solution, coating-sintering of metal alkoxide, andcoating-sintering of colloidal solution of metal oxide (colloidalsolution of silicon dioxide and titanium dioxide) are convenient andpreferred.

The sealing member 7 is preferably an elastic material mainly composedof rubber polymer formed of a copolymer of isobutylene, isoprene anddivinyl benzene, comprising 0.5 to 20 parts of vulcanizing agent such asperoxide or alkyl phenol formalin resin. In other vulcanizing methodusing other vulcanizing agent than peroxide or alkyl phenol formalinresin (for example, sulfur vulcanization), the rubber elasticity dropssignificantly when left over for a long period in the condition of hightemperature and high humidity, and sufficient sealing performance is notobtained, and as a result the organic conductive material may oxidizeand deteriorate due to invasion of water from outside.

Preferred embodiments of the invention are described below. In theembodiments, a “part” always refers to a “part by weight.”

The composition of the electrolytes used in the embodiments of theinvention and in comparative examples is as follows. As the index ofhydrogen ion concentration of the base of the electrolyte or thehydroxide of the base in an aqueous solution, the pH is expressed as anote. The pH is defined in the formula: pH=-log [hydrogen ionconcentration]. Therefore, if the pH is 13 or less, it means that thehydrogen ion concentration is 1.0×10⁻¹³ mol/dm³ or more. Besides, analuminum foil having a dielectric oxide film formed on the surface atvoltage of 500 V was immersed in the electrolyte (temperature 30° C.).In this state, the spark ignition voltage of electrolyte (that is, thedielectric strength of electrolyte) observed by constant voltage-currentelevation at constant current of 2.0 mA/cm² and the conductivity(measuring temperature 30° C.) are shown.

Electrolyte A

γ-butyrolactone (100 parts), mono-1,2,3,4-tetramethyl imidazoliniumphthalate (30 parts) [note: pH=11.2], o-nitrobenzoic acid (1 part),monobutyl ester phosphate (1 part), boric acid (2 parts), and mannite (2parts) were mixed and dissolved.

The spark voltage was 85 V, and the conductivity was 9.0 mS/cm.

Electrolyte B

γ-butyrolactone (50 parts), ethylene glycol (50 parts), trimethylammonium maleate (5 parts) [note: pH=9.5], trimethylamine phthalate (5parts) [note: pH=9.5], diammonium adipate (3 parts) [note: pH=9.1],boric acid (0.5 part), p-nitrobenzoic acid (1 part), and phosphoric acid(0.5 part) were mixed and dissolved.

The spark voltage was 180 V, and the conductivity was 3.3 mS/cm.

Electrolyte C

Ethylene glycol (70 parts), glycerin (30 pats), diammonium adipate (15parts) [note: pH=9.1], 1,6-decane dicarboxylic acid (1 part) [note:pH=9.1], 1,7-octane dicarboxylic acid (1 part) (note: pH=9.1],o-nitrophenol (1 part), and ammonium hypophosphite (1 part) [note:pH=9.1] were mixed and dissolved.

The spark voltage was 340 V, and the conductivity was 0.9 mS/cm.

Electrolyte D:

γ-butyrolactone (100 parts) and tetramethyl ammonium phthalate (40parts) [note: pH=13.2] were mixed and dissolved.

The spark voltage was 79 V, and the conductivity was 11.5 mS/cm.

The sealing members of rubber used in the embodiments of the inventionand comparative examples are as follows.

Sealing member A [vulcanization by peroxide]

It was vulcanized and formed by mixing 30 parts of rubber polymercomposed of a copolymer of isobutylene, isoprene and divinyl benzene, 20parts of carbon, 50 parts of inorganic filler, and 2 parts of dicumylperoxide as a vulcanizing agent. The hardness of the sealing memberafter forming was measured on the surface portion at the side contactingwith the capacitor element between two rubber holes for penetrating alead, and the surface of the portion contacting with the lead wire sideof the rubber hole inside. As a result, the IRHD (international rubberhardness degree) was respectively 67 IRHD and 66 IRHD.

Sealing member B [vulcanization by resin]

It was vulcanized and formed by mixing 30 parts of rubber polymercomposed of a copolymer of isobutylene and isoprene, 20 parts of carbon,50 pats of inorganic filler, and 2 parts of alkyl phenol formalin resinas vulcanizing agent. The hardness of the sealing member after formingwas measured on the surface portion at the side contacting with thecapacitor element between two rubber holes for penetrating a lead, andthe surface of the portion contacting with the lead wire side of therubber hole inside. As a result, the IRHD (international rubber hardnessdegree) was respectively 77 IRHD and 76 IRHD.

Embodiment 1

An anode aluminum foil and a cathode aluminum foil were wound around anelectrolytic paper containing Manila hemp fibers (density 0.55 g/cm³,thickness 50 μm). Thus prepared winding type aluminum electrolyticcapacitor was kept at temperature of 300° C. for 30 minutes, and theelectrolytic paper was carbonized. Then, this capacitor element wasimmersed in a water-ethanol solution containing ethylene dioxythiophenand ferric sulfate, and lifted, and polymerized (10 minutes at 105° C.),and this process was repeated 10 times. The solid organic conductivematerial layer composed of polyethylene dioxythiophen thus polymerizedchemically was formed on the electrode foils and between electrodefoils. Consequently, the capacitor element was washed in water, anddried. Further, electrolyte A was impregnated in this capacitor element.As a result, an aluminum electrolytic capacitor element with ratedvoltage of 50 V and electrostatic capacity of 390 μF was obtained. Thiscapacitor element was put in an aluminum metallic case together withsealing member A, and the opening was sealed by curling process. Thus,an aluminum electrolytic capacitor was composed (size: φ13 mm×L 20 mm).

Embodiment 2

A glass fiber nonwoven cloth (density 0.13 g/cm³, thickness 50 μm), ananode aluminum foil, and a cathode aluminum foil were immersed in awater-ethanol solution containing pyrrole and ammonium persulfate, andlifted, dried and polymerized (10 minutes at 105° C.), and this processwas repeated three times. Thus, a chemically polymerized polypyrrole wasformed. Then, washing in water and drying, the separator made conductiveby the chemically polymerized polypyrrole, and the anode aluminum foiland cathode aluminum foil having the chemically polymerized polypyrroleformed on the surface were obtained. Then, through this conductiveseparator, the anode aluminum foil and cathode aluminum foil having thechemically polymerized polypyrrole formed on the surface were wound, anda capacitor element was formed. It was further immersed in solublesulfonated polyaniline solution at concentration of 10 wt. %,impregnated at reduced pressure, lifted, and dried. Thus, the residualdried sulfonated polyaniline was formed between the anode aluminum foiland cathode aluminum foil having chemically polymerized polypyrrole.Thus, the electric bonding between the electrode foils was reinforced.Still more, this capacitor element was impregnated in electrolyte A. Asa result, an aluminum electrolytic capacitor element with rated voltageof 50 V and electrostatic capacity of 390 μF was obtained. Thiscapacitor element was put in an aluminum metallic case together withsealing member A, and the opening was sealed by curling process. Thus,an aluminum electrolytic capacitor was composed (size: φ13 mm×L 20 mm).

Embodiment 3

On a glass fiber nonwoven cloth (density 0.13 g/cm³, thickness 50 μm),an anode aluminum foil, and a cathode aluminum foil,7,7,8,8-tetracyanoquinodimethane complex in molten state was appliedindividually. Then, by cooling, the separator made conductive by the7,7,8,8-tetracyanoquinodimethane complex, and the anode aluminum foiland cathode aluminum foil having the 7,7,8,8-tetracyanoquinodimethanecomplex formed on the surface were obtained. Then, through thisconductive separator, the anode aluminum foil and cathode aluminum foilhaving the 7,7,8,8-tetracyanoquinodimethane complex formed on thesurface were wound. Thus a capacitor element was formed. It was furtherimmersed in soluble sulfonated polyaniline solution at concentration of10 wt. %, impregnated at reduced pressure, lifted, and dried at atemperature below the melting point of the7,7,8,8-tetracyanoquinodimethane complex. Thus, the residual driedsulfonated polyaniline was formed between the anode aluminum foil andcathode aluminum foil having the 7,7,8,8-tetracyanoquinodimethanecomplex. Thus, the electric bonding between the electrode foils wasreinforced. Still more, this capacitor element was impregnated inelectrolyte A. As a result, an aluminum electrolytic capacitor elementwith rated voltage of 50 V and electrostatic capacity of 390 μF wasobtained. This capacitor element was put in an aluminum metallic casetogether with sealing member A, and the opening was sealed by curlingprocess. Thus, an aluminum electrolytic capacitor was composed (size:φ13 mm×L 20 mm).

Embodiment 4

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that electrolyte B was used as the electrolyte inembodiment 1 of the invention.

Embodiment 5

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that electrolyte C was used as the electrolyte inembodiment 1 of the invention.

Embodiment 6

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that electrolyte D was used as the electrolyte inembodiment 1 of the invention.

Embodiment 7

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that sealing member B was used as the sealing memberin embodiment 1 of the invention.

Embodiment 8

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that pyrrole was used instead of ethylenedioxythiophen in embodiment 1 of the invention.

Embodiment 9

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that aniline was used instead of ethylenedioxythiophen in embodiment 1 of the invention.

Embodiment 10

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that a mixture of iron p-toluene sulfonate and irondodecyl benzene sulfonate was used instead of ferric sulfate, and thatwater-methanol solution was used instead of water-ethanol solution inembodiment 1 of the invention.

Embodiment 11

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that a mixture of ammonium persulfate and hydrogenpersulfate water was used instead of ferric sulfate in embodiment 1 ofthe invention.

Comparative Example 1

An anode aluminum foil and a cathode aluminum foil were wound around anelectrolytic paper containing Manila hemp fibers (density 0.55 g/cm³,thickness 50 μm). Thus a capacitor element was prepared. This capacitorelement was impregnated in electrolyte A, and an aluminum electrolyticcapacitor element with rated voltage of 50 V and electrostatic capacityof 390 μF was obtained. This capacitor element was put in an aluminummetallic case together with sealing member A. Then the opening wassealed by curling process. Thus, an aluminum electrolytic capacitor wascomposed (size: φ13 mm×L 20 mm).

Comparative Example 2

An electrolytic capacitor was prepared in the same manner as inembodiment 1 except that electrolyte A was not impregnated in embodiment1 of the invention.

Comparative Example 3

An anode aluminum foil and a cathode aluminum foil were wound around anelectrolytic paper containing Manila hemp fibers (density 0.55 g/cm³,thickness 50 μm). Thus a capacitor element was prepared. This capacitorelement was kept at temperature of 300° C. for 30 minutes, and theelectrolytic paper was carbonized. Then this element was immersed in7,7,8,8-tetracyanoquinodimethane complex in molten state and impregnatedat reduced pressure. By cooling, a 7,7,8,8-tetracyanoquinodimethanecomplex layer was formed directly between the electrodes. Thus, analuminum electrolytic capacitor element with rated voltage of 50 V andelectrostatic capacity of 390 μF was obtained. This capacitor elementwas put in an aluminum metallic case together with sealing member A, andthe opening was sealed by curling process. Thus, an aluminumelectrolytic capacitor was composed (size: φ13 mm×L 20 mm).

Comparative Example 4

An anode aluminum foil and a cathode aluminum foil were wound around aglass fiber nonwoven cloth (density 0.13 g/cm³, thickness 50 μm), andthe obtained aluminum electrolytic capacitor element was immersed in anaqueous solution of manganese nitrate, lifted, and pyrolyzed (10 minutesat 300° C.), and this process was repeated 10 times, and a manganesedioxide layer which is a solid inorganic conductive material wasdirectly formed between the electrodes. This capacitor element wasimpregnated in electrolyte A. Thus, an aluminum electrolytic capacitorelement with rated voltage of 50 V and electrostatic capacity of 390 μFwas obtained. This capacitor element was put in an aluminum metalliccase together with sealing member A, and the opening was sealed bycurling process. Thus, an aluminum electrolytic capacitor was composed(size: φ13 mm×L 20 mm).

Comparative Example 5

An electrolytic capacitor was prepared in the same manner as incomparative example 1 except that carbon fabric weaving carbon fiberswas used instead of the electrolytic paper in comparative example 1.

Comparative Example 6

An electrolytic capacitor was prepared in the same manner as incomparative example 1 except that glass fiber nonwoven cloth coated withwater dispersion type colloidal graphite was used instead of theelectrolytic paper in comparative example 1.

Table 1 shows results of comparison of initial characteristics(electrostatic capacity, impedance leak current) and number of shortingtroubles during aging process in aluminum electrolytic capacitors inembodiments 1 to 11 of the invention and comparative examples 1 to 6.

In each material, the number of samples was 20, and the initialcharacteristic (except for shorting troubles) is expressed by theaverage of 20 samples.

TABLE 1 Leak current Number of Electrostatic (μA) at shorting capacityrated troubles Impedance (μF) voltage, during (mΩ) f = 120 Hz 2 minaging f = 400 kHz Embodiment 1 390 92 0 10 Embodiment 2 390 90 0 11Embodiment 3 370 93 0 11 Embodiment 4 393 90 0 12 Embodiment 5 385 88 022 Embodiment 6 380 180  0 10 Embodiment 7 390 89 0 11 Embodiment 8 39089 0 12 Embodiment 9 384 90 0 13 Embodiment 10 360 91 0 13 Embodiment 11380 91 0 11 Comparative 395 70 0 41 example 1 Comparative 360 1000  15 15 example 2 or more Comparative 385 1000  18  13 example 3 or moreComparative 385 195  2 18 example 4 Comparative 380 170  0 30 example 5Comparative 390 1000  17  25 example 6 or more

As clear from Table 1, the electrolytic capacitors in embodiments 1 to11 of the invention is extremely small in impedance as compared with theelectrolytic capacitor composed only of electrolyte in comparativeexample 1.

In the aluminum electrolytic capacitor lowered in resistance by usingcarbon fabric weaving carbon fibers as means of making the separatorconductive in comparative example 5, the impedance is improved ascompared with comparative example 1, but the impedance is larger than inthe electrolytic capacitors in embodiments 1 to 11.

In the electrolytic capacitors in the comparative examples, that is, inthe aluminum electrolytic capacitor not having electrolyte using onlyconductive high polymer (polyethylene dioxythiophen layer) incomparative example 2, in the aluminum electrolytic capacitor not havingelectrolyte using only organic semiconductor(7,7,8,8-tetracyanoquinodimethane complex layer) in comparative example3, and in the aluminum electrolytic capacitor lowered in resistance byapplying water-dispersion type colloidal graphite as the conductivemeans of separator in comparative example 6, shorting troubles (shortingbetween electrodes due to lack of dielectric strength) occurred in allsamples during aging process for applying a direct voltage of 63 V attemperature of 85° C.

In the aluminum electrolytic capacitor using manganese dioxide which isa solid inorganic conductive material, instead of solid organicconductive material, in comparative example 4, although the impedance isexcellent, since the conductive material is inorganic, the electrolyte,which is an organic matter, is hardly diffused, and the restorationperformance of the dielectric oxide film was not assured sufficiently.Accordingly, slight shorting troubles occurred during aging.

As explained herein, the invention presents, in a simple process,electrolytic capacitors having excellent characteristics, such asexcellent impedance characteristic, small leak current, superiorreliability, and high dielectric strength. Of the embodiments of theinvention, in embodiment 6 of the invention using electrolyte D, sincethe spark ignition voltage of electrolyte is below 80 V, the dielectricstrength is not sufficient, and the leak current value tends to behigher as compared with other embodiments although shorting did notoccur during aging. Therefore, to express the effects of the inventionsufficiently in the aspects of dielectric strength and leak current, thespark ignition voltage of the electrolyte is preferred to be 80 V ormore.

Of the embodiments of the invention, in embodiment 5 of the inventionusing electrolyte C, since the conductivity of the electrolyte is lessthan 1.0 mS/cm, the conductivity is not sufficient, and the impedancetends to be higher as compared with other embodiments. In order toexpress the effects of the invention sufficiently in the aspect ofimpedance performance, the conductivity of the electrolyte is preferredto be 1.0 mS/cm or more.

Table 2 shows the results of observation of the sealing member surfaceafter 1000 hours of continuous application test of rated voltage of 50 Vin the atmosphere of temperature of 60° C. and relative humidity of 95%,in aluminum electrolytic capacitors in embodiments 1 to 11 of theinvention. The number of samples is 20 each.

TABLE 2 Appearance of sealing member surface after 1000 hours ofhumidity resistance test at 60° C., 95% RH Embodiment 1 No abnormalityEmbodiment 2 No abnormality Embodiment 3 No abnormality Embodiment 4 Noabnormality Embodiment 5 No abnormality Embodiment 6 Electrolyte leak in2 samples Embodiment 7 No abnormality Embodiment 8 No abnormalityEmbodiment 9 No abnormality Embodiment 10 No abnormality Embodiment 11No abnormality

As clear from Table 2, extreme abnormality was not observed in anyembodiment. However, in embodiment 6 using electrolyte D, since the baseof the electrolytic material is a base of strong basicity with hydrogenion concentration of less than 1.0×10⁻¹³ mol/dm³, in the long-term testin complex environments of high temperature and high humidity, thesealing member (sealing portion) is likely to be damaged by the effectsof the base of strong basicity, and, as a result, electrolyte leak wasobserved in two samples. The electrolyte leaks from the lead. In orderto express the effects of the invention sufficiently in the aspect ofreliability, in the base for composing the electrolytic substance, theconcentration of the base or the hydroxide of the base is preferred tobe 1 wt. % or more, and when the measuring temperature is 30° C., thehydrogen ion concentration of the base or the hydroxide of the base inaqueous solution is preferred to be selected at 1.0×10⁻¹³ mol/dm³ ormore.

According to the method of embodiments 1 to 11 of the invention andcomparative examples 2 and 3, again, aluminum electrolytic capacitorelements with rated voltage of 6.3 V and electrostatic capacity of 1000μF were obtained. This capacitor element was put in a aluminum metalliccase together with the sealing member A. Then the opening was sealed bycurling process. Consequently, a resin seat plate made of polyphenylenesulfide was mounted. As a result, an aluminum electrolytic capacitor ofvertical surface mounting type was fabricated (size: φ10 mm×L 10 mm).Thus composed aluminum electrolytic capacitor of surface mounting typewas mounted on a glass epoxy substrate (2 mm thick) by using creamsolder (Sn—Pb eutectic composition). By passing through a reflow furnacefor infrared and hot air treatment (peak temperature 240° C., exposuretime to temperature of 200° C. or more of 50 seconds), mounting and heatresistance test was conducted. The number of samples was 20.

As a result, the surface mounting type aluminum electrolytic capacitorscomposed in the methods conforming to embodiments 1 to 11 of theinvention were suppressed in pressure elevation in the capacitor due towater adsorbed on the members because the electrolyte was composed of anorganic solvent with boiling point of 200° C. or more added to solidorganic conductive material as electrolytic substance. Hence, mountingtroubles due to scatter of sealing member of swelling of sealing memberdid not occur. On the other hand, in the surface mounting type aluminumelectrolytic capacitors composed in the methods conforming tocomparative examples 2 and 3, the pressure elevation in the capacitordue to adsorbed water was extreme, and the sealing members scattered inall 20 samples. Evidently, the surface mounting type aluminumelectrolytic capacitors manufactured in the methods of the embodimentsof the invention were enhanced in heat resistance when mounting, byusing the electrolyte composed of organic solvent of boiling point of200° C. or more, in addition to the solid organic conductive material.

Thus, the electrolytic capacitors of the invention have excellentcharacteristics such as excellent impedance characteristic, small leakcurrent, excellent reliability, and high dielectric strength. Hence, itsindustrial values are outstanding.

What is claimed is:
 1. An electrolytic capacitor comprising: (a) acapacitor element having a positive electrode, a negative electrode, anda solid organic conductive material, said capacitor element arrangedsuch that said positive electrode and negative electrode define a regiontherebetween, (b) an electrolyte, (c) a case for accommodating saidcapacitor element and said electrolyte, and (d) a sealing memberdisposed to cover an opening of said case, wherein said solid organicconductive material is disposed so that said solid organic conductivematerial fills said region between said positive electrode and saidnegative electrode such that said solid organic conductive materialfunctions as a solid electrolyte.
 2. An electrolytic capacitor of claim1, wherein said positive electrode comprises a metal foil and adielectric oxide film formed on the surface of said metal foil, and hasa valve action.
 3. An electrolytic capacitor of claim 1, wherein saidcase is formed of a tubular metal having a bottom.
 4. An electrolyticcapacitor of claim 1, wherein said solid organic conductive material hasa conductive polymer.
 5. An electrolytic capacitor of claim 4, whereinsaid conductive polymer has a polymer of at least one monomer selectedfrom the group consisting of pyrrole, aniline, thiophen, ethylenedioxythiophen, sulfonated aniline, sulfonated pyrrole, sulfonatedthiophen, sulfonated ethylene dioxythiophen, and their derivatives. 6.An electrolytic capacitor of claim 4, wherein said conductive polymerhas at least one polymer selected from the group consisting ofliquid-phase chemical polymerization composition, vapor-phasepolymerization composition, liquid-phase electrolytic polymerizationcomposition, and residual dry polymer of soluble polymer solution.
 7. Anelectrolytic capacitor of claim 5, wherein said conductive polymer hasat least one polymer formed by chemically polymerizing selected from thegroup consisting of polypyrrole, polyethylene dioxythiophen, andpolyaniline.
 8. An electrolytic capacitor of claim 5, wherein saidconductive polymer has at least one polymer formed by electrolyticallypolymerizing selected from the group consisting of polypyrrole,polyethylene dioxythiophen, and polyaniline.
 9. An electrolyticcapacitor of claim 1, wherein said solid organic conductive material isat least one selected from the group consisting of organic semiconductorand conductive polymer, and a residual dry polymer of soluble sulfonatedpolyaniline solution.
 10. An electrolytic capacitor of claim 1, whereinsaid electrolyte has an organic solvent, and at least one electrolyticsubstance of organic salt and inorganic salt dissolved in said organicsolvent.
 11. An electrolytic capacitor of claim 10, wherein said solidorganic conductive material is swollen in said organic solvent.
 12. Anelectrolytic capacitor of claim 10, wherein said electrolyte has atleast one selected from the group consisting of a compound having alkylsubsistent amidine group, quaternary salt of compound having alkylsubstituent amidine group, tertiary amine, and ammonium.
 13. Anelectrolytic capacitor of claim 12, wherein said electrolyte has saidquaternary salt of compound having alkyl substituent amidine group, thealkyl substituent of said quaternary salt of compound having alkylsubstituent amidine group is one selected from the group consisting ofalkyl group and aryl alkyl group with 1 to 11 carbon atoms, and thecompound having the amidine group of said quaternary salt of thecompound having alkyl substituent amidine group is at least one selectedfrom the group consisting of imidazole compound, benzoimidazolecompound, and alicyclic amidine compound.
 14. An electrolytic capacitorof claim 10, wherein said electrolyte has at least one property selectedfrom the group consisting of: (1) boiling point is 200° C. or more, (2)electric conductivity at measuring temperature of 30° C. is 1.0 mS/cm ormore, and (3) spark ignition voltage is 80 V or more.
 15. Theelectrolytic capacitor of claim 1, wherein said solid organic conductivematerial is disposed on at least one of said positive electrode and saidnegative electrode.
 16. The electrolytic capacitor of claim 1, whereinsaid solid organic conductive material is disposed at least one of inand on said separator, and further, said solid organic conductivematerial is disposed on at least one of said positive electrode and saidnegative electrode.
 17. The electrolytic capacitor of claim 1, whereinsaid electrolyte includes a solvent and an electrolytic substance, andsaid electrolytic substance is dissolved in said solvent.
 18. Anelectrolytic capacitor comprising: (a) a capacitor element having apositive electrode, a negative electrode, and a solid organic conductivematerial, said capacitor element arranged such that said positiveelectrode and negative electrode define a region therebetween, (b) anelectrolyte, (c) a case for accommodating said capacitor element andsaid electrolyte, and (d) a sealing member disposed to cover an openingof said case, wherein said solid organic conductive material is disposedso that said solid organic conductive material fills said region betweensaid positive electrode and said negative electrode such that said solidorganic conductive material functions as a solid electrolyte, whereinsaid solid organic conductive material has an organic semiconductormaterial.
 19. An electrolytic capacitor of claim 18, wherein saidorganic semiconductor material is at least one selected from the groupconsisting of 7,7,8,8-tetracyanoquinodimethane complex and itsderivatives.
 20. An electrolytic capacitor comprising: (a) a capacitorelement having a positive electrode, a negative electrode, and a solidorganic conductive material disposed between said positive electrode andsaid negative electrode, (b) an electrolyte, (c) a case foraccommodating said capacitor element and said electrolyte, and (d) asealing member disposed to cover an opening of said case, wherein saidsolid organic conductive material has an organic semiconductor materialand a conductive polymer.
 21. An electrolytic capacitor comprising: (a)a capacitor element having a positive electrode, a negative electrode,and a solid organic conductive material, said capacitor element arrangedsuch that said positive electrode and negative electrode define a regiontherebetween, (b) an electrolyte, (c) a case for accommodating saidcapacitor element and said electrolyte, and (d) a sealing memberdisposed to cover an opening of said case, wherein said solid organicconductive material is disposed so that said solid organic conductivematerial fills said region between said positive electrode and saidnegative electrode such that said solid organic conductive materialfunctions as a solid electrolyte, wherein said solid organic conductivematerial has a conductive polymer, wherein said conductive polymer has aresidual dry polymer of soluble sulfonated polyaniline solution.
 22. Anelectrolytic capacitor comprising: (a) a capacitor element having apositive electrode, a negative electrode, and a solid organic conductivematerial disposed between said positive electrode and said negativeelectrode, (b) an electrolyte, (c) a case for accommodating saidcapacitor element and said electrolyte, and (d) a sealing memberdisposed to cover an opening of said case, wherein said electrolyte hasan organic solvent, and at least one electrolytic substance of organicsalt and inorganic salt dissolved in said organic solvent, wherein abase of said at least one electrolytic substance has a hydrogen ionconcentration of 1.0×10⁻¹³ mol/dm³ or more in 1 wt. % aqueous solutionof the base or hydroxide of the base.
 23. An electrolytic capacitorcomprising: (a) a capacitor element having a positive electrode, anegative electrode, and a solid organic conductive material disposedbetween said positive electrode and said negative electrode, (b) anelectrolyte, (c) a case for accommodating said capacitor element andsaid electrolyte, and (d) a sealing member disposed to cover an openingof said case wherein said electrolyte has an organic solvent, and atleast one electrolytic substance of organic salt and inorganic saltdissolved in said organic solvent, wherein said electrolyte has at leasta quaternary salt of the compound having alkyl substituent amidine groupselected from the group consisting of: 1-methyl-1, 8-diazabicyclo[5,4,0] undecene-7, 1-methyl-1, 5-diazabicyclo [4,3,0] nonene-5,1,2,3-trimethyl imidazolinium, 1,2,3,4-tetramethyl imidazolinium,1,2-dimethyl-3-ethyl-imidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 1,3-dimethyl-2-heptyl imidazolinium, 1,3-dimethyl-2-(-3′heptyl) imidazolinium, 1,3-dimethyl-2-dodecyl imidazolinium,1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidium, 1,3-dimethyl imidazolium,1-methyl-3-ethyl-imidazolium, and 1,3-dimethyl benzoimidazolium.
 24. Anelectrolytic capacitor comprising: (a) a capacitor element having apositive electrode, a negative electrode, and a solid organic conductivematerial, said capacitor element arranged such that said positiveelectrode and negative electrode define a region therebetween, (b) anelectrolyte, (c) a case for accommodating said capacitor element andsaid electrolyte, and (d) a sealing member disposed to cover an openingof said case, wherein said solid organic conductive material is disposedso that said solid organic conductive material fills said region betweensaid positive electrode and said negative electrode such that said solidorganic conductive material functions as a solid electrolyte, saidelectrolytic capacitor further comprising a separator between saidpositive electrode and said negative electrodes, wherein said solidorganic conductive material is disposed on surfaces of said positiveelectrode and said negative electrode, and in said separator, saidelectrolyte includes a solvent and electrolytic substance, and saidelectrolyte is disposed in said solid organic conductive material andsaid separator at a state of swelling said solid organic conductivematerial and said separator.
 25. An electrolytic capacitor comprising:(a) a capacitor element having a positive electrode, a negativeelectrode, and a solid organic conductive material disposed between saidpositive electrode and said negative electrode, (b) an electrolyte, and(c) a case for accommodating said capacitor element and saidelectrolyte, wherein said solid organic conductive material is formed onat least one of said positive electrode and said negative electrode,wherein at least one of said positive electrode and said negativeelectrode has a dielectric oxide film formed on a surface thereof,wherein said dielectric oxide film has a roughening surface, and saidsolid organic conductive material is disposed in a hollow place of saidroughening surface of said dielectric oxide film.
 26. An electrolyticcapacitor comprising: (a) a capacitor element having a positiveelectrode, a negative electrode, and a solid organic conductive materialdisposed between said positive electrode and said negative electrode,(b) an electrolyte, and (c) a case for accommodating said capacitorelement and said electrolyte, wherein said solid organic conductivematerial is formed on at least one of said positive electrode and saidnegative electrode.
 27. The electrolytic capacitor of claim 26, furthercomprising a separator disposed between said positive electrode and saidnegative electrode.
 28. The electrolytic capacitor of claim 26, whereinsaid electrolyte is disposed between said positive electrode and saidnegative electrode.
 29. The electrolytic capacitor of claim 26, whereinsaid solid organic conductive material has at least one of an organicsemiconductor material and a conductive polymer.
 30. The electrolyticcapacitor of claim 26, further comprising a sealing member disposed atan opening of said case.
 31. The electrolytic capacitor of claim 26,wherein at least one of said positive electrode and said negativeelectrode has a dielectric oxide film formed on a surface thereof. 32.The electrolytic capacitor of claim 26, wherein said solid organicconductive material has a function of a solid electrolyte.
 33. Theelectrolytic capacitor of claim 26, wherein said electrolyte includes asolvent and electrolytic substance, and said electrolytic substance isdissolved in said solvent.
 34. The electrolytic capacitor of claim 26,wherein said solid organic conductive material is disposed so that saidsolid organic conductive material fills between said positive electrodeand said negative electrode.
 35. The electrolytic capacitor of claim 26,further comprising a separator between said positive electrode and saidnegative electrode, wherein said solid organic conductive material isdisposed further in said separator, said electrolyte includes a solventand electrolytic substance, and said electrolyte is disposed in saidsolid organic conductive material and said separator at a state ofswelling said solid organic conductive material and said separator. 36.An electrolytic capacitor comprising: (a) a capacitor element having apositive electrode, a negative electrode, and a solid organic conductivematerial disposed between said positive electrode and said negativeelectrode, (b) a separator disposed between said positive electrode andsaid negative electrode, (c) an electrolyte, and (d) a case foraccommodating said capacitor element and said electrolyte, wherein saidsolid organic conductive material is disposed at least one of in and onsaid separator, and further said solid organic conductive material isdisposed on at least one of said positive electrode and said negativeelectrode.
 37. The electrolytic capacitor of claim 36, wherein saidelectrolyte is disposed between said positive electrode and saidnegative electrode.
 38. The electrolytic capacitor of claim 36, whereinsaid solid organic conductive material has at least one of an organicsemiconductor material and a conductive polymer.
 39. The electrolyticcapacitor of claim 36, further comprising a sealing member disposed atan opening of said case.
 40. The electrolytic capacitor of claim 36,wherein at least one of said positive electrode and said negativeelectrode has a dielectric oxide film formed on a surface thereof. 41.The electrolytic capacitor of claim 40, wherein said dielectric oxidefilm has a roughening surface, and said solid organic conductivematerial is disposed in a hollow place of said roughening surface ofsaid dielectric oxide film.
 42. The electrolytic capacitor of claim 36,wherein said solid organic conductive material has a function of a solidelectrolyte.
 43. The electrolytic capacitor of claim 36, wherein saidelectrolyte includes a solvent and electrolytic substance, and saidelectrolytic substance is dissolved in said solvent.
 44. Theelectrolytic capacitor of claim 36, wherein said solid organicconductive material is disposed so that said solid organic conductivematerial fills between said positive electrode and said negativeelectrode.
 45. The electrolytic capacitor of claim 36, wherein saidsolid organic conductive material is disposed in said separator, saidelectrolyte includes a solvent and electrolytic substance, and saidelectrolyte is disposed in said solid organic conductive material andsaid separator at a state of swelling said solid organic conductivematerial and said separator.